Alternating-current motor



v. A. FYNN. ALTERNATING CURRENT MOTOR.

APPLlCATlON FILED DEC.15, 1916.

1,345,538. a ent d July 6, 1920.

I /NVENTOR ATTORNEY v UNITED STATES PATENT orriciz.

VALERE A. FYNN, OF ST. LOUIS, MISSOURI, ASSIGNOR TO WAGNER ELECTRIC MANU- FACTURING COMPANY, OF ST. LOUIS, MISSOURI, A CORPORATION OF MISSOURI.

ALTERNATING-CURRENT MOTOR.

Specification of Letters Patent.

Patented July 6, 1920.

Application filed December 15, 1916. Serial No. 137,103.

United States of America, have invented a certain new and useful Alternating-Current Motor, of wluch the following is such a tull. clear, and exact description as will enable anyone skilled in the art to which it appertains' to make and use the same, reference being had to the accompanying drawings, forming part of this specification.

My invention relates to single-phase commutator motors of the induction type and has for its object to make it possible to adjust the speed of these machines in a simple manner.

In carrying out my invention I provide the secondary or induced member'with a single commuted winding, and dispose on same two sets of working brushes, impressing an alternating current E. M. F. on each set and making provision for so moving the brushes as to increase .or decrease the peripheral distance between the brushes con nected to the same ELM. F.,' preferably without changing the axis of the. rotor circuit of which these brushes form a part. In order to excite the machine, I provide another circuit through the rotor, displaced from the working circuit. and in case I utilize the same commuted winding for this purpose, I either provide additional brushes or make use of the working brushes already referred to, for the purpose of forming an exciting circuit through the rotor.

In the accompanying drawings. Figure 1 is a diagrammatic representation of a twopole" compensated single-phase induction commutator motor embodying my invention. While Fig. 2 shows a modification of same.

Referring to Fig. 1, the stator carries a main inducing winding 4 connected to the mains 2, 3, also a coaxial compensating winding 21. The rotor is provided with-a commuted winding 6, with which cooperates the working brushes 6, 7, 8, 9 and the exciting brushes 10, 11. The brushes 6, 9 are insulatingly supported by the rocker arm 12, and the brushes 7 8 are similarly sup-,

ported by the rocker arm 13. vThese. rocker arms are under the control of the rod 19'. being connected thereto by means ot'the links 14, 15, pivoted at 16 17, 18. When the rod 19 is moved to the rig t, the rocker arms 12, 13 move in opposite directions and the angle formed by each with the axis of the main inducing winding 1 is increased.

When the rod 19 is moved in the oppositedirection, this angle is decreased for both rocker arms, and they approach a position in' which their axes coincide with that of the main inducing winding 4. In'other words, when the rod 19 is moved to the left. then the number of rotor conductors included between the brushes (3, 8, and be tween the brushes 7, 9, is increased,and the chords spanned bythese brushes become longer. hen the rod 19 is moved to the right, the number of conductors lying between the brushes 7, 9 and between the brushes 6, 8, is diminished, and the chords spanned by said brushes become shorter. An E. M IF. derived from the transformer 24. the primary of which is connected to the mains 2, 3, is impressed by way of thesecondary 25 on the brushes (3, 8, and an E. M. F. of same phase and same magnitude, derived from the same transformer by way of the secondary 26, is impressed on the brushes 7, 9. The brushes 6, 8 and 7, 9 are so connected to the respective transformer secondaries 25 and 26, that the magnitude and direction of the E. M. F. conductivelyv impressed on them, can be changed.

The excitin brushes 11, 19 are fixed in space and located along an axis displaced by 90 electrical degrees with respect to that of the main inducing winding 1. They are connected to the compensating winding 21 by way of the fixed point 22 located somewhere in the middle of that winding and of the movable contact. 23, thus enabling the magnitude of this compensating E. M. F."

ondaries 25,- 26 of the transformer 24:, and

then-'move the rod 19 in one or the other direction, thus increasing or decreasing the active number of conductors within each of the rotor working circuits While keeping the' axis of these circuits coincident with that of the main inducing winding. At the same time, I may adjust the power factor of the machine by suitably adjusting, by means of the movable contact 23, the magnitude of the compensating E. M. F. impressed on the exciting circuit of the rotor through the brushes 10, 11. Whenever the speed range to be secured is not too great it is only necessary to move the working brushes and sometimes to change the direction of the E. M. F.s coiuluctively introduced into the rotor working circuits to obtain any of the desired speeds. But in order to secure a wider range of speeds, particularly speeds much below the synchronous, I prefer also to vary the magnitude of these E. M. F.s.

The machine of Fig. 2 differs from that of Fig. 1 in that the exciting brushes 10, 11 are omitted and the working brushes 6, 8 and 7 9 are utilized for the purpose of controlling the rotor working as well as the rotor exciting circuits. To this end the compensating winding 21' is connected, through the fixed contact 22 and'the movable contact 23, to the middle points of the secondaries which supply the E. M. F.s conductively introduced into the rotor working circuits. The direction of these E. M. F.s is controlled by the reversing switch 27; and their magnitude is controlled b changing thenumber of primary turns 0 the transformer 2-4, from the secondaries 25, 26 of which said E. M. F.s are derived. In this modification the working currents. flow in those portions of the rotor commuted winding which are located on the are lying between the brushes 6, 8 on one side and the brushes 7, 9 on the other, whereas the rotor exciting currents flow in those parts of the rotor commuated windingwhich are located on the arcs siuated between the brushes 6, 7 on one side and the brushes 8,.9 on the other. lVhen the rod 19 is moved to the-right, then -the efiective rotor conductors in the working circuit are reduced, while the efi'ective rotor conductors in the exciting circuit are increased. For a movement of the rod 19 in the opposite direction, the reverse is true.

he mode of operation of a motor, embodying my invention, is somewhat as follows:

Brushes cooperating with the commuted winding 5 and located in the axis of the main inducing winding 4, contact with the winding 5;at oints where the value of the working E. F. induced by the winding 4 1s a maximum. If these brushes are now so moved as to remain on a-hne parallel to the axis of 4 but to gradually span a shorter and shorter arc of the winding 5 then the working E. M. 'F. appearing at the brushes will gradually diminish, becoming zero when the two brushes come together on an axis displaced by 90 electrical degrees from that of 4. The, E. M. F. actually induced in 5 by 4 will, of course, remain constant as long as the E. M. F. im-

between them,

pressed on 4 is constant. If brushes, moved in the way which has just been described, are short circuited on themselves, then their movement ,Will not affect the speed of the machine, which will remain nearly synchronous throu hout; but if an alternatlng current E. M. of constant value is conductively introduced into the circuit of such brushes, for instance, into the circuit of the brushes 6, 8 and these brushes are moved toward each other, then the efiective working E. M. F., that is the al ebraical sum of the rotor working M. appearing at these brushes and of .the conductively introduced working E. M. R, will gradually decrease, because the effective rotor E. M. I. decreases. This decrease chan es the ratio between th effective rotor E. F. and the conductively impressed E. M. F. and thus alters the speed of the machine. It is, of course, not necessary to have two sets of brushes such as 6, 8 and 7, 9. One set only, for instance, the brushes 6, 8 may be used, .but in that case the rotor copper will not be as fully utilized. It is also not absolutely necessary to keep the axes of the rotor Working circuits at all times parallel with the axis of the main inducing winding, but the better results are usually obtained in this way. If the axes of the rotor working circuits are allowed to form an appreciable angle with the axis of the main inducing winding 4, then the rotor working currents will also contribute to the production of the torque-producing field along the motor axis 10, 11, and this may at times lead to unwelcome complications When the conductively impressed E. M. F.s are so applied as to be of same'direction as the statically induced working the machine will be increased, being. decreased if the direction of the conductively introduced E. M. F.s is reversed.

Referring more particularly to Fig. 2, where the brushes cooperating with the commuted winding 5 carry working as well as exciting currents, the brushes 6, 7, and the E. M. F.s, then the speed of.

brushes 8, 9 should not be broughtnearer to each other than a certain predetermined distance, as otherwise ighe exciting current will reach undesirably high values. Furthermore, these brushes must in this case never coincide in position, for this would immediately annul the motor field and short circuit the compensating winding 21. Since a movement of the brushes in this figure also changes the number of active it will be necessary to vary the magnitude of the compensating E. M. F. with varying brush position, in order to keep control of the power factor of the machine, for this power factor willvary with the ratio of rotor field turns to the number of active turns of the compensating winding 21.

Having fully described my invention,

what' I claim as new and desire to secure by Letters Patent of the United States is:

1. In an alternating current motor, the combination of an inducing member, an induced member provided with a commuted winding, means for establishing a working circuit through said winding, means for establishing an exciting circuit through said windingthe current in which is independent of the current in the working circuit, means for conductively supplying an E. M. F. to'

the working circuit, and means for changing the number of conductors of the commuted winding included in the working circuit without changing the axis of said circuit.

2. In analternating current motor, the combination of an inducing member, an induced member provided with a commuted winding, means for-establishing a working circuit through said winding, means for establishing an exciting circuit through said winding-the current in which is independent of the current in the working circuit, said working and exciting circuits being displaced by ninety electrical degrees from each other and the axis of the working circuit coinciding with the axis of the magnetization produded by the inducing member,

meansfor conductively supplying an E, M;

F. to' the working circuit, and meansfor changing the number of conductors of the commuted winding included'in the working circuit without changing the axis of said circuit. 2

3. In an alternating current motor, the combination of'an inducing member, an in duced member provided with a commuted .winding, means for establishing a working of E. M. F.

combination of an inducing member, an in duced member provided, with a commuted winding, exciting brushes and working brushes cooperating with said winding, means for conductively impressingon the 1 working circuit an E. M. F. substantially co-phasal with the E, F. impressed on theinducing member, and means forshifti-ng thepositionof the working brushes without changing their axis.

5. In an alternating current motor the combination of an inducing member, an induced member provided with a commuted 'wmdlng, two sets'of brushes for establishing working circuits through the induced member, each set being coaxial with the magnetization produced by the inducing member, two brush-carrying members, each supporting one brush of each set and each being pivoted at a point intermediate the; brushes which it supports, means for simultaneously rotating said brush-carriers in op: posite directions on their pivots, and means for'conductively impressing an E. M. F. on each working circuit.

-6. In an alternating current motor the.

combination of an inducing member, an induced member provided with a commuted.

winding, exciting brushes and working brushes cooperating with said winding,

means for conductively impressing an E M. F. on. the working circuits, means for shifting the positions of the working brushes without changing their axes, and

means for impressing a compensating E. M.

'F. on the exciting brushes.

7. The combination with a source of E.

M. F., of an alternating current motor comprising an, inducing member, an induced member provided with a commuted winding, two sets of brushes cooperating with the commuted winding'to establish workingcircuits, a transformer connected to'the source and having twosecondary windings, each secondarywinding being in c1rcuit with one of the sets of brushes, and means for shifting the position of'each set of brushes without changing its axis.

In testimony whereof I have hereunto set my hand and aflixed my seal;

VALERE"A. FYNN. [1,. s] 

